/* (N)compress42.c - File compression ala IEEE Computer, Mar 1992.
 *
 * Authors:
 *   Spencer W. Thomas   (decvax!harpo!utah-cs!utah-gr!thomas)
 *   Jim McKie           (decvax!mcvax!jim)
 *   Steve Davies        (decvax!vax135!petsd!peora!srd)
 *   Ken Turkowski       (decvax!decwrl!turtlevax!ken)
 *   James A. Woods      (decvax!ihnp4!ames!jaw)
 *   Joe Orost           (decvax!vax135!petsd!joe)
 *   Dave Mack           (csu@alembic.acs.com)
 *   Peter Jannesen, Network Communication Systems
 *                       (peter@ncs.nl)
 *
 * Revision 4.2.3  92/03/14 peter@ncs.nl
 *   Optimise compress and decompress function and a lot of cleanups.
 *   New fast hash algoritme added (if more than 800Kb available).
 *
 * Revision 4.1  91/05/26 csu@alembic.acs.com
 *   Modified to recursively compress directories ('r' flag). As a side
 *   effect, compress will no longer attempt to compress things that
 *   aren't "regular" files. See Changes.
 *
 * Revision 4.0  85/07/30  12:50:00  joe
 *   Removed ferror() calls in output routine on every output except first.
 *   Prepared for release to the world.
 *
 * Revision 3.6  85/07/04  01:22:21  joe
 *   Remove much wasted storage by overlaying hash table with the tables
 *   used by decompress: tab_suffix[1<<BITS], stack[8000].  Updated USERMEM
 *   computations.  Fixed dump_tab() DEBUG routine.
 *
 * Revision 3.5  85/06/30  20:47:21  jaw
 *   Change hash function to use exclusive-or.  Rip out hash cache.  These
 *   speedups render the megamemory version defunct, for now.  Make decoder
 *   stack global.  Parts of the RCS trunks 2.7, 2.6, and 2.1 no longer apply.
 *
 * Revision 3.4  85/06/27  12:00:00  ken
 *   Get rid of all floating-point calculations by doing all compression ratio
 *   calculations in fixed point.
 *
 * Revision 3.3  85/06/24  21:53:24  joe
 *   Incorporate portability suggestion for M_XENIX.  Got rid of text on #else
 *   and #endif lines.  Cleaned up #ifdefs for vax and interdata.
 *
 * Revision 3.2  85/06/06  21:53:24  jaw
 *   Incorporate portability suggestions for Z8000, IBM PC/XT from mailing list.
 *   Default to "quiet" output (no compression statistics).
 *
 * Revision 3.1  85/05/12  18:56:13  jaw
 *   Integrate decompress() stack speedups (from early pointer mods by McKie).
 *   Repair multi-file USERMEM gaffe.  Unify 'force' flags to mimic semantics
 *   of SVR2 'pack'.  Streamline block-compress table clear logic.  Increase
 *   output byte count by magic number size.
 *
 * Revision 3.0   84/11/27  11:50:00  petsd!joe
 *   Set HSIZE depending on BITS.  Set BITS depending on USERMEM.  Unrolled
 *   loops in clear routines.  Added "-C" flag for 2.0 compatibility.  Used
 *   unsigned compares on Perkin-Elmer.  Fixed foreground check.
 *
 * Revision 2.7   84/11/16  19:35:39  ames!jaw
 *   Cache common hash codes based on input statistics; this improves
 *   performance for low-density raster images.  Pass on #ifdef bundle
 *   from Turkowski.
 *
 * Revision 2.6   84/11/05  19:18:21  ames!jaw
 *   Vary size of hash tables to reduce time for small files.
 *   Tune PDP-11 hash function.
 *
 * Revision 2.5   84/10/30  20:15:14  ames!jaw
 *   Junk chaining; replace with the simpler (and, on the VAX, faster)
 *   double hashing, discussed within.  Make block compression standard.
 *
 * Revision 2.4   84/10/16  11:11:11  ames!jaw
 *   Introduce adaptive reset for block compression, to boost the rate
 *   another several percent.  (See mailing list notes.)
 *
 * Revision 2.3   84/09/22  22:00:00  petsd!joe
 *   Implemented "-B" block compress.  Implemented REVERSE sorting of tab_next.
 *   Bug fix for last bits.  Changed fwrite to putchar loop everywhere.
 *
 * Revision 2.2   84/09/18  14:12:21  ames!jaw
 *   Fold in news changes, small machine typedef from thomas,
 *   #ifdef interdata from joe.
 *
 * Revision 2.1   84/09/10  12:34:56  ames!jaw
 *   Configured fast table lookup for 32-bit machines.
 *   This cuts user time in half for b <= FBITS, and is useful for news batching
 *   from VAX to PDP sites.  Also sped up decompress() [fwrite->putc] and
 *   added signal catcher [plus beef in write_error()] to delete effluvia.
 *
 * Revision 2.0   84/08/28  22:00:00  petsd!joe
 *   Add check for foreground before prompting user.  Insert maxbits into
 *   compressed file.  Force file being uncompressed to end with ".Z".
 *   Added "-c" flag and "zcat".  Prepared for release.
 *
 * Revision 1.10  84/08/24  18:28:00  turtlevax!ken
 *   Will only compress regular files (no directories), added a magic number
 *   header (plus an undocumented -n flag to handle old files without headers),
 *   added -f flag to force overwriting of possibly existing destination file,
 *   otherwise the user is prompted for a response.  Will tack on a .Z to a
 *   filename if it doesn't have one when decompressing.  Will only replace
 *   file if it was compressed.
 *
 * Revision 1.9  84/08/16  17:28:00  turtlevax!ken
 *   Removed scanargs(), getopt(), added .Z extension and unlimited number of
 *   filenames to compress.  Flags may be clustered (-Ddvb12) or separated
 *   (-D -d -v -b 12), or combination thereof.  Modes and other status is
 *   copied with copystat().  -O bug for 4.2 seems to have disappeared with
 *   1.8.
 *
 * Revision 1.8  84/08/09  23:15:00  joe
 *   Made it compatible with vax version, installed jim's fixes/enhancements
 *
 * Revision 1.6  84/08/01  22:08:00  joe
 *   Sped up algorithm significantly by sorting the compress chain.
 *
 * Revision 1.5  84/07/13  13:11:00  srd
 *   Added C version of vax asm routines.  Changed structure to arrays to
 *   save much memory.  Do unsigned compares where possible (faster on
 *   Perkin-Elmer)
 *
 * Revision 1.4  84/07/05  03:11:11  thomas
 *   Clean up the code a little and lint it.  (Lint complains about all
 *   the regs used in the asm, but I'm not going to "fix" this.)
 *
 * Revision 1.3  84/07/05  02:06:54  thomas
 *   Minor fixes.
 *
 * Revision 1.2  84/07/05  00:27:27  thomas
 *   Add variable bit length output.
 *
 */

/*
 * $Id$
 *
 * 2004-05-27 Claudio Matsuoka <claudio@conectiva.com>
 * - initial ELKS port
 * - some source code reformatting
 * - worked around bcc bugs
 *
 * 2004-06-03 Claudio Matsuoka <claudio@conectiva.com>
 * - placing tables back in BSS, build with bcc -X-H0xe000
 *
 * 2004-06-04 Claudio Matsuoka <claudio@conectiva.com>
 * - removed workaround for bcc bug (fixed in bcc 0.16.16)
 */
#define ELKS
#define LSTAT
#define DIRENT
#define UTIME_H
#include <ctype.h>
#include "mutils.h"

#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <limits.h>
#ifdef __GNUC__
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#endif

#ifdef DIRENT
#  include <dirent.h>
#  define RECURSIVE 1
#  undef SYSDIR
#endif

#ifdef SYSDIR
#  include <sys/dir.h>
#  define RECURSIVE 1
#endif

#ifdef UTIME_H
#  include <utime.h>
#else
struct utimbuf {
	time_t actime;
	time_t modtime;
};
#endif

#ifdef	__STDC__
#  define ARGS(a) a
#else
#  define ARGS(a) ()
#endif

#define	LARGS(a) ()	/* Relay on include files for libary func defs. */

#ifndef SIG_TYPE
#  define SIG_TYPE void (*)()
#endif

static char ident[] = "(N)compress 4.2.4";
#define version_id (ident)

#undef	min
#define	min(a,b)	((a>b) ? b : a)

#ifndef	IBUFSIZ
#  define IBUFSIZ BUFSIZ	/* Default input buffer size	*/
#endif
#ifndef	OBUFSIZ
#  define OBUFSIZ BUFSIZ	/* Default output buffer size	*/
#endif

#define MAXPATHLEN PATH_MAX	/* MAXPATHLEN - maximum length of a	*/
				/*  pathname we allow 			*/
#define	SIZE_INNER_LOOP	256	/* Size of the inter (fast) compress loop */

/* Defines for third byte of header */
#define	MAGIC_1	(char_type)'\037'	/* First byte of compressed file  */
#define	MAGIC_2	(char_type)'\235'	/* Second byte of compressed file */
#define BIT_MASK 0x1f		/* Mask for 'number of compresssion bits' */
				/* Masks 0x20 and 0x40 are free.	  */
				/* I think 0x20 should mean that there is */
				/* a fourth header byte (for expansion).  */

#define BLOCK_MODE 0x80		/* Block compresssion if table is full	*/
				/* and compression rate is dropping	*/
				/* flush tables	*/

/* the next two codes should not be changed lightly, as they must not	*/
/* lie within the contiguous general code space.			*/
#define FIRST	257		/* first free entry 			*/
#define	CLEAR	256		/* table clear output code		*/

#define INIT_BITS 9		/* initial number of bits/code		*/

#ifndef SACREDMEM
	/*
 	 * SACREDMEM is the amount of physical memory saved for others;
	 * compress will hog the rest.
 	 */
#	define SACREDMEM	0
#endif

#ifndef USERMEM
	/*
 	 * Set USERMEM to the maximum amount of physical user memory
	 * available in bytes. USERMEM is used to determine the maximum
	 * BITS that can be used for compression.
	 */
#	define USERMEM 	450000	/* default user memory */
#endif

#ifndef	BYTEORDER
#  define BYTEORDER 0000
#endif

#ifndef	NOALLIGN
#  define NOALLIGN 0
#endif


/*
 * machine variants which require cc -Dmachine:  pdp11, z8000, DOS
 */

#ifdef interdata		/* Perkin-Elmer				*/
#  define SIGNED_COMPARE_SLOW	/* signed compare slower than unsigned	*/
#endif

#ifdef pdp11	 		/* PDP11: don't forget to compile with -i */
#  define BITS 12		/* max bits/code for 16-bit machine	*/
#  define NO_UCHAR		/* also if "unsigned char" functions as */
				/* signed char				*/
#endif /* pdp11 */

#ifdef z8000			/* Z8000: 				*/
#  define BITS 12		/* 16-bits processor max 12 bits	*/
#  undef vax			/* weird preprocessor			*/
#endif /* z8000 */

#ifdef	DOS			/* PC/XT/AT (8088) processor		*/
#  define BITS 16		/* 16-bits processor max 12 bits	*/
#  if BITS == 16
#    define MAXSEG_64K
#  endif
#  undef BYTEORDER
#  define BYTEORDER 4321
#  undef NOALLIGN
#  define NOALLIGN 1
#  define COMPILE_DATE	__DATE__
#endif /* DOS */

#ifdef ELKS
#  pragma GCC diagnostic ignored "-Wstrict-aliasing"
#  define BITS 12		/* 16-bits processor max 12 bits	*/
#  undef BYTEORDER
#  define BYTEORDER 4321	/* CM: FIXME: Assumes little-endian ELKS */
#  undef NOALLIGN
#  define NOALLIGN 1
#  define COMPILE_DATE	__DATE__
#endif

#ifndef	O_BINARY
#  define O_BINARY 0		/* System has no binary mode		*/
#endif

#ifdef M_XENIX			/* Stupid compiler can't handle arrays with */
#  if BITS == 16 		/* more than 65535 bytes - so we fake it */
#    define MAXSEG_64K
#  else
#    if BITS > 13		/* Code only handles BITS = 12, 13, or 16 */
#      define BITS 13
#    endif
#  endif
#endif

#ifndef BITS		/* General processor calculate BITS */
#  if USERMEM >= (800000+SACREDMEM)
#    define FAST
#  else
#    if USERMEM >= (433484+SACREDMEM)
#	define BITS	16
#    else
#	if USERMEM >= (229600+SACREDMEM)
#	  define BITS	15
#	else
#	  if USERMEM >= (127536+SACREDMEM)
#	    define BITS	14
#   	  else
#	    if USERMEM >= (73464+SACREDMEM)
#	      define BITS	13
#	    else
#	      define BITS	12
#	    endif
#	  endif
#      endif
#    endif
#  endif
#endif /* BITS */

#ifdef FAST
#  define HBITS		17		/* 50% occupancy */
#  define HSIZE	   (1<<HBITS)
#  define HMASK	   (HSIZE-1)
#  define HPRIME		 9941
#  define BITS		   16
#  undef MAXSEG_64K
#else
#  if BITS == 16
#    define HSIZE	69001		/* 95% occupancy */
#  endif
#  if BITS == 15
#    define HSIZE	35023		/* 94% occupancy */
#  endif
#  if BITS == 14
#    define HSIZE	18013		/* 91% occupancy */
#  endif
#  if BITS == 13
#    define HSIZE	9001		/* 91% occupancy */
#  endif
#  if BITS <= 12
#    define HSIZE	5003		/* 80% occupancy */
#  endif
#endif

#define CHECK_GAP 10000

typedef long int		code_int;

#ifdef SIGNED_COMPARE_SLOW
typedef unsigned long int	count_int;
typedef unsigned short int	count_short;
typedef unsigned long int	cmp_code_int;	/* Cast to make compare faster	*/
#else
typedef long int		count_int;
typedef long int		cmp_code_int;
#endif

typedef	unsigned char	char_type;

#define ARGVAL() (*++(*argv) || (--argc && *++argv))

#define MAXCODE(n)	(1L << (n))

#ifndef	REGISTERS
#	define	REGISTERS	2
#endif
#define	REG1
#define	REG2
#define	REG3
#define	REG4
#define	REG5
#define	REG6
#define	REG7
#define	REG8
#define	REG9
#define	REG10
#define	REG11
#define	REG12
#define	REG13
#define	REG14
#define	REG15
#define	REG16
#if REGISTERS >= 1
#	undef	REG1
#	define	REG1	register
#endif
#if REGISTERS >= 2
#	undef	REG2
#	define	REG2	register
#endif
#if REGISTERS >= 3
#	undef	REG3
#	define	REG3	register
#endif
#if REGISTERS >= 4
#	undef	REG4
#	define	REG4	register
#endif
#if REGISTERS >= 5
#	undef	REG5
#	define	REG5	register
#endif
#if REGISTERS >= 6
#	undef	REG6
#	define	REG6	register
#endif
#if REGISTERS >= 7
#	undef	REG7
#	define	REG7	register
#endif
#if REGISTERS >= 8
#	undef	REG8
#	define	REG8	register
#endif
#if REGISTERS >= 9
#	undef	REG9
#	define	REG9	register
#endif
#if REGISTERS >= 10
#	undef	REG10
#	define	REG10	register
#endif
#if REGISTERS >= 11
#	undef	REG11
#	define	REG11	register
#endif
#if REGISTERS >= 12
#	undef	REG12
#	define	REG12	register
#endif
#if REGISTERS >= 13
#	undef	REG13
#	define	REG13	register
#endif
#if REGISTERS >= 14
#	undef	REG14
#	define	REG14	register
#endif
#if REGISTERS >= 15
#	undef	REG15
#	define	REG15	register
#endif
#if REGISTERS >= 16
#	undef	REG16
#	define	REG16	register
#endif


union	bytes
{
	long	word;
	struct {
#if BYTEORDER == 4321
		char_type	b1;
		char_type	b2;
		char_type	b3;
		char_type	b4;
#else
#  if BYTEORDER == 1234
		char_type	b4;
		char_type	b3;
		char_type	b2;
		char_type	b1;
#  else
#	undef	BYTEORDER
		int				dummy;
#  endif
#endif
	} bytes;
};

/* CM: You need bcc 0.16.16 or later to compile this */
#if BYTEORDER == 4321 && NOALLIGN == 1
# define output(b,o,c,n) { \
    *(long *)&((b)[(o)>>3]) |= ((long)(c))<<((o)&0x07); \
    (o) += (n); \
  }
#else
#  ifdef BYTEORDER
#    define output(b,o,c,n) { \
	REG1 char_type *p = &(b)[(o)>>3]; \
	union bytes i; \
	i.word = ((long)(c))<<((o)&0x07)); \
	p[0] |= i.bytes.b1; \
	p[1] |= i.bytes.b2; \
	p[2] |= i.bytes.b3; \
	(o) += (n); \
     }
#  else
#    define output(b,o,c,n) { \
	REG1 char_type *p = &(b)[(o)>>3]; \
	REG2 long i = ((long)(c))<<((o)&0x07); \
	p[0] |= (char_type)(i);	\
	p[1] |= (char_type)(i>>8); \
	p[2] |= (char_type)(i>>16); \
	(o) += (n); \
     }
#  endif
#endif

/* CM: You need bcc 0.16.16 or later to compile this */
#if BYTEORDER == 4321 && NOALLIGN == 1
#  define input(b,o,c,n,m) { \
     (c) = (*(long *)(&(b)[(o)>>3])>>((o)&0x07)) & (m); \
     (o) += (n); \
   }
#else
#  define input(b,o,c,n,m) { \
     REG1 char_type *p = &(b)[(o)>>3]; \
     (c) = ((((long)(p[0]))|((long)(p[1])<<8)| \
	   ((long)(p[2])<<16))>>((o)&0x7))&(m);	\
     (o) += (n); \
   }
#endif


char	*progname;		/* Program name				*/
int 	silent = 0;		/* don't tell me about errors		*/
int	quiet = 1;		/* don't tell me about compression	*/
int	do_decomp = 0;		/* Decompress mode			*/
int	force = 0;		/* Force overwrite of files and links	*/
int	nomagic = 0;		/* Use a 3-byte magic number header,	*/
				/* unless old file			*/
int	block_mode = BLOCK_MODE;/* Block compress mode -C compatible with 2.0*/
int	maxbits = BITS;		/* user settable max # bits/code 	*/
int 	zcat_flg = 0;		/* Write output on stdout, suppress messages*/
int	recursive = 0;  	/* compress directories			*/
int	exit_code = -1;		/* Exitcode of compress (-1 no file compressed)*/

char_type	inbuf[IBUFSIZ+64];	/* Input buffer			*/
char_type	outbuf[OBUFSIZ+2048];	/* Output buffer		*/

struct stat	infstat;		/* Input file status		*/
char		*ifname;		/* Input filename		*/
int		remove_ofname = 0;	/* Remove output file on a erro	*/
char 		ofname[MAXPATHLEN];	/* Output filename		*/
int		fgnd_flag = 0;		/* Running in background (SIGINT=SIGIGN)*/

long 		bytes_in;	/* Total number of byte from input	*/
long 		bytes_out;	/* Total number of byte to output	*/

/*
 * 8086 & 80286 Has a problem with array bigger than 64K so fake the array
 * For processors with a limited address space and segments.
 */
/*
 * To save much memory, we overlay the table used by compress() with those
 * used by decompress().  The tab_prefix table is the same size and type
 * as the codetab.  The tab_suffix table needs 2**BITS characters.  We
 * get this from the beginning of htab.  The output stack uses the rest
 * of htab, and contains characters.  There is plenty of room for any
 * possible stack (stack used to be 8000 characters).
 */
#ifdef MAXSEG_64K
	count_int htab0[8192];
	count_int htab1[8192];
	count_int htab2[8192];
	count_int htab3[8192];
	count_int htab4[8192];
	count_int htab5[8192];
	count_int htab6[8192];
	count_int htab7[8192];
	count_int htab8[HSIZE-65536];
	count_int * htab[9] = {htab0,htab1,htab2,htab3,htab4,htab5,htab6,htab7,htab8};

	unsigned short code0tab[16384];
	unsigned short code1tab[16384];
	unsigned short code2tab[16384];
	unsigned short code3tab[16384];
	unsigned short code4tab[16384];
	unsigned short * codetab[5] = {code0tab,code1tab,code2tab,code3tab,code4tab};

#	define	htabof(i)		(htab[(i) >> 13][(i) & 0x1fff])
#	define	codetabof(i)		(codetab[(i) >> 14][(i) & 0x3fff])
#	define	tab_prefixof(i)		codetabof(i)
#	define	tab_suffixof(i)		((char_type *)htab[(i)>>15])[(i) & 0x7fff]
#	define	de_stack		((char_type *)(&htab2[8191]))
	void	clear_htab() {
		memset(htab0, -1, sizeof(htab0));
		memset(htab1, -1, sizeof(htab1));
		memset(htab2, -1, sizeof(htab2));
		memset(htab3, -1, sizeof(htab3));
		memset(htab4, -1, sizeof(htab4));
		memset(htab5, -1, sizeof(htab5));
		memset(htab6, -1, sizeof(htab6));
		memset(htab7, -1, sizeof(htab7));
		memset(htab8, -1, sizeof(htab8));
	}
#	define	clear_tab_prefixof()	memset(code0tab, 0, 256);
#else	/* Normal machine */
	count_int	htab[HSIZE];
	unsigned short	codetab[HSIZE];

#	define	htabof(i)		htab[i]
#	define	codetabof(i)		codetab[i]
#	define	tab_prefixof(i)		codetabof(i)
#	define	tab_suffixof(i)		((char_type *)(htab))[i]
#	define	de_stack		((char_type *)&(htab[HSIZE-1]))
#	define	clear_htab()		memset(htab, -1, sizeof(htab))
#	define	clear_tab_prefixof()	memset(codetab, 0, 256);
#endif	/* MAXSEG_64K */

#ifdef FAST
	int primetab[256] =		/* Special secudary hash table.	*/
	{
    	 1013, -1061, 1109, -1181, 1231, -1291, 1361, -1429,
    	 1481, -1531, 1583, -1627, 1699, -1759, 1831, -1889,
    	 1973, -2017, 2083, -2137, 2213, -2273, 2339, -2383,
    	 2441, -2531, 2593, -2663, 2707, -2753, 2819, -2887,
    	 2957, -3023, 3089, -3181, 3251, -3313, 3361, -3449,
    	 3511, -3557, 3617, -3677, 3739, -3821, 3881, -3931,
    	 4013, -4079, 4139, -4219, 4271, -4349, 4423, -4493,
    	 4561, -4639, 4691, -4783, 4831, -4931, 4973, -5023,
    	 5101, -5179, 5261, -5333, 5413, -5471, 5521, -5591,
    	 5659, -5737, 5807, -5857, 5923, -6029, 6089, -6151,
    	 6221, -6287, 6343, -6397, 6491, -6571, 6659, -6709,
    	 6791, -6857, 6917, -6983, 7043, -7129, 7213, -7297,
    	 7369, -7477, 7529, -7577, 7643, -7703, 7789, -7873,
    	 7933, -8017, 8093, -8171, 8237, -8297, 8387, -8461,
    	 8543, -8627, 8689, -8741, 8819, -8867, 8963, -9029,
    	 9109, -9181, 9241, -9323, 9397, -9439, 9511, -9613,
    	 9677, -9743, 9811, -9871, 9941,-10061,10111,-10177,
	10259,-10321,10399,-10477,10567,-10639,10711,-10789,
  	10867,-10949,11047,-11113,11173,-11261,11329,-11423,
   	11491,-11587,11681,-11777,11827,-11903,11959,-12041,
   	12109,-12197,12263,-12343,12413,-12487,12541,-12611,
   	12671,-12757,12829,-12917,12979,-13043,13127,-13187,
   	13291,-13367,13451,-13523,13619,-13691,13751,-13829,
   	13901,-13967,14057,-14153,14249,-14341,14419,-14489,
   	14557,-14633,14717,-14767,14831,-14897,14983,-15083,
   	15149,-15233,15289,-15359,15427,-15497,15583,-15649,
   	15733,-15791,15881,-15937,16057,-16097,16189,-16267,
   	16363,-16447,16529,-16619,16691,-16763,16879,-16937,
   	17021,-17093,17183,-17257,17341,-17401,17477,-17551,
   	17623,-17713,17791,-17891,17957,-18041,18097,-18169,
   	18233,-18307,18379,-18451,18523,-18637,18731,-18803,
   	18919,-19031,19121,-19211,19273,-19381,19429,-19477
	};
#endif

int  	main		ARGS((int,char **));
void  	Usage		ARGS((void));
void  	comprexx	ARGS((char **));
void  	compdir		ARGS((char *));
void  	compress	ARGS((int,int));
void  	decompress	ARGS((int,int));
void  	read_error	ARGS((void));
void  	write_error	ARGS((void));
void 	abort_compress	ARGS((void));
void  	prratio		ARGS((FILE *,long,long));
void  	about		ARGS((void));

/*****************************************************************
 * TAG( main )
 *
 * Algorithm from "A Technique for High Performance Data Compression",
 * Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19.
 *
 * Usage: compress [-dfvc] [-b bits] [file ...]
 * Inputs:
 *   -d:     If given, decompression is done instead.
 *
 *   -c:     Write output on stdout, don't remove original.
 *
 *   -b:     Parameter limits the max number of bits/code.
 *
 *   -f:     Forces output file to be generated, even if one already
 *           exists, and even if no space is saved by compressing.
 *           If -f is not used, the user will be prompted if stdin is
 *           a tty, otherwise, the output file will not be overwritten.
 *
 *   -v:     Write compression statistics
 *
 *   -r:     Recursive. If a filename is a directory, descend
 *           into it and compress everything in it.
 *
 * file ...:
 *           Files to be compressed.  If none specified, stdin is used.
 * Outputs:
 *   file.Z:     Compressed form of file with same mode, owner, and utimes
 *   or stdout   (if stdin used as input)
 *
 * Assumptions:
 *   When filenames are given, replaces with the compressed version
 *   (.Z suffix) only if the file decreases in size.
 *
 * Algorithm:
 *   Modified Lempel-Ziv method (LZW).  Basically finds common
 *   substrings and replaces them with a variable size code.  This is
 *   deterministic, and can be done on the fly.  Thus, the decompression
 *   procedure needs no input table, but tracks the way the table was built.
 */
int
main(argc, argv)
	REG1	int 	 argc;
	REG2	char	*argv[];
{
    	REG3	char	**filelist;
	REG4	char	**fileptr;

	if ((fgnd_flag = (signal(SIGINT, SIG_IGN)) != SIG_IGN))
		signal(SIGINT, (SIG_TYPE)abort_compress);

	signal(SIGTERM, (SIG_TYPE)abort_compress);
#ifndef DOS
	signal(SIGHUP, (SIG_TYPE)abort_compress);
#endif

#ifdef COMPATIBLE
    	nomagic = 1;	/* Original didn't have a magic number */
#endif

    	filelist = fileptr = (char **)malloc(argc*sizeof(char *));
    	*filelist = NULL;

	if ((progname = strrchr(argv[0], '/')) != 0)
		progname++;
	else
		progname = argv[0];

    	if (strcmp(progname, "uncompress") == 0)
		do_decomp = 1;
	else if (strcmp(progname, "zcat") == 0)
		do_decomp = zcat_flg = 1;

    	/* Argument Processing
     	 * All flags are optional.
     	 * -V => print Version; debug verbose
     	 * -d => do_decomp
     	 * -v => unquiet
     	 * -f => force overwrite of output file
     	 * -n => no header: useful to uncompress old files
     	 * -b maxbits => maxbits.  If -b is specified, then maxbits MUST be given also.
     	 * -c => cat all output to stdout
     	 * -C => generate output compatible with compress 2.0.
     	 * -r => recursively compress directories
     	 * if a string is left, must be an input filename.
     	 */

    	for (argc--, argv++; argc > 0; argc--, argv++) {
		if (**argv == '-') {/* A flag argument */
		    	while (*++(*argv)) {/* Process all flags in this arg */
				switch (**argv) {
			    	case 'V':
					about();
					break;

				case 's':
					silent = 1;
					quiet = 1;
					break;

			    	case 'v':
					silent = 0;
					quiet = 0;
					break;

			    	case 'd':
					do_decomp = 1;
					break;

			    	case 'f':
			    	case 'F':
					force = 1;
					break;

			    	case 'n':
					nomagic = 1;
					break;

			    	case 'C':
					block_mode = 0;
					break;

			    	case 'b':
					if (!ARGVAL()) {
					    	fprintf(stderr, "Missing maxbits\n");
					    	Usage();
					}

					maxbits = atoi(*argv);
					goto nextarg;

		    		case 'c':
					zcat_flg = 1;
					break;

			    	case 'q':
					quiet = 1;
					break;
			    	case 'r':
			    	case 'R':
#ifdef	RECURSIVE
					recursive = 1;
#else
					fprintf(stderr, "%s -r not availble (du to missing directory functions)\n", *argv);
#endif
					break;

			    	default:
					fprintf(stderr, "Unknown flag: '%c'; ", **argv);
					Usage();
				}
		    	}
		} else {
		    	*fileptr++ = *argv;	/* Build input file list */
		    	*fileptr = NULL;
		}

nextarg:	continue;
   	}

    	if (maxbits < INIT_BITS)	maxbits = INIT_BITS;
    	if (maxbits > BITS) 		maxbits = BITS;

    	if (*filelist != NULL) {
      		for (fileptr = filelist; *fileptr; fileptr++)
			comprexx(fileptr);
    	} else {/* Standard input */
		ifname = "";
		exit_code = 0;
		remove_ofname = 0;

		if (do_decomp == 0) {
			compress(0, 1);

			if (zcat_flg == 0 && !quiet) {
				fprintf(stderr, "Compression: ");
				prratio(stderr, bytes_in-bytes_out, bytes_in);
					fprintf(stderr, "\n");
			}

			if (bytes_out >= bytes_in && !(force))
				exit_code = 2;
		} else
			decompress(0, 1);
	}

	exit((exit_code== -1) ? 1:exit_code);
}

void
Usage()
{
	fprintf(stderr, "\
Usage: %s [-dfvcVr] [-b maxbits] [file ...]\n\
       -d   If given, decompression is done instead.\n\
       -c   Write output on stdout, don't remove original.\n\
       -b   Parameter limits the max number of bits/code.\n", progname);
		fprintf(stderr, "\
       -f   Forces output file to be generated, even if one already.\n\
            exists, and even if no space is saved by compressing.\n\
            If -f is not used, the user will be prompted if stdin is.\n\
            a tty, otherwise, the output file will not be overwritten.\n\
       -v   Write compression statistics.\n\
       -V   Output vesion and compile options.\n\
       -r   Recursive. If a filename is a directory, descend\n\
            into it and compress everything in it.\n");

    	exit(1);
}

void
comprexx(fileptr)
	char	**fileptr;
{
	int		fdin;
	int		fdout;
	char	tempname[MAXPATHLEN];

	strcpy(tempname,*fileptr);
	errno = 0;

#ifdef LSTAT
	if (lstat(tempname,&infstat) == -1)
#else
	if (stat(tempname,&infstat) == -1)
#endif
	{
	  	if (do_decomp) {
	    		switch (errno) {
		    	case ENOENT:	/* file doesn't exist */
	      			/*
	      			** if the given name doesn't end with .Z, try appending one
	      			** This is obviously the wrong thing to do if it's a
	      			** directory, but it shouldn't do any harm.
	      			*/
		      		if (strcmp(tempname + strlen(tempname) - 2, ".Z") != 0) {
					strcat(tempname,".Z");
					errno = 0;
#ifdef	LSTAT
					if (lstat(tempname,&infstat) == -1)
#else
					if (stat(tempname,&infstat) == -1)
#endif
					{
					  	perror(tempname);
						exit_code = 1;
					  	return;
					}

					if ((infstat.st_mode & S_IFMT) != S_IFREG) {
						fprintf(stderr, "%s: Not a regular file.\n", tempname);
						exit_code = 1;
						return ;
					}
		      		} else {
					perror(tempname);
					exit_code = 1;
					return;
		      		}

		      		break;

	    		default:
		      		perror(tempname);
					exit_code = 1;
		      		return;
	    		}
	  	} else {
	      		perror(tempname);
			exit_code = 1;
	      		return;
	  	}
	}

	switch (infstat.st_mode & S_IFMT) {
	case S_IFDIR:	/* directory */
#ifdef	RECURSIVE
	  	if (recursive)
		    	compdir(tempname);
	  	else
#endif
			if (!quiet)
			    	fprintf(stderr,"%s is a directory -- ignored\n", tempname);
		break;

	case S_IFREG:	/* regular file */
		  	if (do_decomp != 0)
			{/* DECOMPRESSION */
		    	if (!zcat_flg) {
			      	if (strcmp(tempname + strlen(tempname) - 2, ".Z") != 0) {
					if (!quiet)
		  				fprintf(stderr,"%s - no .Z suffix\n",tempname);
					return;
	      			}
		    	}

			strcpy(ofname, tempname);

			/* Strip of .Z suffix */

			if (strcmp(tempname + strlen(tempname) - 2, ".Z") == 0)
				ofname[strlen(tempname) - 2] = '\0';
	   	} else {/* COMPRESSION */
		    	if (!zcat_flg) {
				if (strcmp(tempname + strlen(tempname) - 2, ".Z") == 0) {
		 			fprintf(stderr, "%s: already has .Z suffix -- no change\n", tempname);
		  			return;
				}

				if (infstat.st_nlink > 1 && (!force)) {
			  		fprintf(stderr, "%s has %d other links: unchanged\n",
						tempname, (int)(infstat.st_nlink - 1));
						exit_code = 1;
			  			return;
				}
			}

			strcpy(ofname, tempname);
			strcat(ofname, ".Z");
    		}

	    	if ((fdin = open(ifname = tempname, O_RDONLY|O_BINARY)) == -1) {
		      	perror(tempname);
			exit_code = 1;
			return;
	    	}

    		if (zcat_flg == 0) {
			int				c;
			int				s;
			struct stat		statbuf;
			struct stat		statbuf2;

			if (stat(ofname, &statbuf) == 0) {
				if ((s = strlen(ofname)) > 8) {
					c = ofname[s-1];
					ofname[s-1] = '\0';

					statbuf2 = statbuf;

					if (!stat(ofname, &statbuf2) &&
						statbuf.st_mode  == statbuf2.st_mode &&
						statbuf.st_ino   == statbuf2.st_ino &&
						statbuf.st_dev   == statbuf2.st_dev &&
						statbuf.st_uid   == statbuf2.st_uid &&
						statbuf.st_gid   == statbuf2.st_gid &&
						statbuf.st_size  == statbuf2.st_size &&
						statbuf.st_atime == statbuf2.st_atime &&
						statbuf.st_mtime == statbuf2.st_mtime &&
						statbuf.st_ctime == statbuf2.st_ctime) {
							fprintf(stderr, "%s: filename too long to tack on .Z\n", tempname);
							exit_code = 1;
							return;
					}

					ofname[s-1] = (char)c;
				}

				if (!force) {
		    			inbuf[0] = 'n';

		    			fprintf(stderr, "%s already exists.\n", ofname);

		    			if (fgnd_flag && isatty(0)) {
						fprintf(stderr, "Do you wish to overwrite %s (y or n)? ", ofname);
						fflush(stderr);

			    			if (read(0, inbuf, 1) > 0) {
							if (inbuf[0] != '\n') {
								do {
									if (read(0, inbuf+1, 1) <= 0) {
										perror("stdin");
										break;
									}
								} while (inbuf[1] != '\n');
							}
						} else
							perror("stdin");
		    			}

		    			if (inbuf[0] != 'y') {
						fprintf(stderr, "%s not overwritten\n", ofname);
						exit_code = 1;
						return;
		    			}
				}

				if (unlink(ofname)) {
					fprintf(stderr, "Can't remove old output file\n");
					perror(ofname);
					exit_code = 1;
					return ;
				}
			}

		    	if ((fdout = open(ofname, O_WRONLY|O_CREAT|O_EXCL|O_BINARY,0600)) == -1) {
			      	perror(tempname);
					return;
		    	}

			if ((s = strlen(ofname)) > 8) {
				if (fstat(fdout, &statbuf)) {
					fprintf(stderr, "Can't get status op output file\n");
					perror(ofname);
					exit_code = 1;
					return ;
				}

				c = ofname[s-1];
				ofname[s-1] = '\0';
				statbuf2 = statbuf;

				if (!stat(ofname, &statbuf2) &&
					statbuf.st_mode  == statbuf2.st_mode &&
					statbuf.st_ino   == statbuf2.st_ino &&
					statbuf.st_dev   == statbuf2.st_dev &&
					statbuf.st_uid   == statbuf2.st_uid &&
					statbuf.st_gid   == statbuf2.st_gid &&
					statbuf.st_size  == statbuf2.st_size &&
					statbuf.st_atime == statbuf2.st_atime &&
					statbuf.st_mtime == statbuf2.st_mtime &&
					statbuf.st_ctime == statbuf2.st_ctime) {
					fprintf(stderr, "%s: filename too long to tack on .Z\n", tempname);

					if (unlink(ofname)) {
						fprintf(stderr, "can't remove bad output file\n");
						perror(ofname);
					}
					exit_code = 1;
					return;
				}

				ofname[s-1] = (char)c;
			}

			if (!quiet)
				fprintf(stderr, "%s: ", tempname);

			remove_ofname = 1;
    		} else {
			fdout = 1;
			ofname[0] = '\0';
			remove_ofname = 0;
		}

    		if (do_decomp == 0)
			compress(fdin, fdout);
    		else
			decompress(fdin, fdout);

		close(fdin);

		if (fdout != 1 && close(fdout))
			write_error();

		if (bytes_in == 0) {
			if (remove_ofname) {
				if (unlink(ofname)) {	/* Remove input file */
					fprintf(stderr, "\nunlink error (ignored) ");
	    				perror(ofname);
					exit_code = 1;
				}

				remove_ofname = 0;
			}
		} else if (zcat_flg == 0) {
		    	struct utimbuf	timep;

			/* No compression: remove file.Z */
		    	if (!do_decomp && bytes_out >= bytes_in && (!force)) {
				if (!quiet)
					fprintf(stderr, "No compression -- %s unchanged\n", ifname);

			    	if (unlink(ofname)) {
					fprintf(stderr, "unlink error (ignored) ");
					perror(ofname);
				}

				remove_ofname = 0;
				exit_code = 2;
		    	} else {	/* ***** Successful Compression ***** */
				if (!quiet) {
					fprintf(stderr, " -- replaced with %s",ofname);

					if (!do_decomp) {
						fprintf(stderr, " Compression: ");
						prratio(stderr, bytes_in-bytes_out, bytes_in);
					}

					fprintf(stderr, "\n");
				}

				timep.actime = infstat.st_atime;
				timep.modtime = infstat.st_mtime;

				if (utime(ofname, &timep)) {
					fprintf(stderr, "\nutime error (ignored) ");
					perror(ofname);
					exit_code = 1;
				}

#ifndef	AMIGA
				/* Copy modes */
				if (chmod(ofname, infstat.st_mode & 07777)) {
					fprintf(stderr, "\nchmod error (ignored) ");
				    	perror(ofname);
					exit_code = 1;
				}
#ifndef	DOS
				/* Copy ownership */
				chown(ofname, infstat.st_uid, infstat.st_gid);
#endif
#endif
				remove_ofname = 0;

				if (unlink(ifname)) {	/* Remove input file */
					fprintf(stderr, "\nunlink error (ignored) ");
    					perror(ifname);
					exit_code = 1;
				}
    			}
    		}

		if (exit_code == -1)
			exit_code = 0;

		break;

	default:
		fprintf(stderr,"%s is not a directory or a regular file - ignored\n",
	  		tempname);
		break;
	}
}

#ifdef RECURSIVE
void
compdir(dir)
	REG3 char *dir;
{
#ifndef	DIRENT
	REG1 struct direct *dp;
#else
	REG1 struct dirent *dp;
#endif
	REG2 DIR *dirp;
	char nbuf[MAXPATHLEN];
	char *nptr = nbuf;

	dirp = opendir(dir);

	if (dirp == NULL) {
		printf("%s unreadable\n", dir);		/* not stderr! */
		return ;
	}
	/*
	** WARNING: the following algorithm will occasionally cause
	** compress to produce error warnings of the form "<filename>.Z
	** already has .Z suffix - ignored". This occurs when the
	** .Z output file is inserted into the directory below
	** readdir's current pointer.
	** These warnings are harmless but annoying. The alternative
	** to allowing this would be to store the entire directory
	** list in memory, then compress the entries in the stored
	** list. Given the depth-first recursive algorithm used here,
	** this could use up a tremendous amount of memory. I don't
	** think it's worth it. -- Dave Mack
	*/

	while ((dp = readdir(dirp)) != NULL) {
		if (dp->d_ino == 0)
			continue;

		if (strcmp(dp->d_name,".") == 0 || strcmp(dp->d_name,"..") == 0)
			continue;

		if ((strlen(dir)+strlen(dp->d_name)+1) < (MAXPATHLEN - 1)) {
		  	strcpy(nbuf,dir);
		  	strcat(nbuf,"/");
		  	strcat(nbuf,dp->d_name);
	  		comprexx(&nptr);
		} else
	  		fprintf(stderr,"Pathname too long: %s/%s\n", dir, dp->d_name);
  		}

	closedir(dirp);

	return;
}
#endif

/*
 * compress fdin to fdout
 *
 * Algorithm:  use open addressing double hashing (no chaining) on the
 * prefix code / next character combination.  We do a variant of Knuth's
 * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
 * secondary probe.  Here, the modular division first probe is gives way
 * to a faster exclusive-or manipulation.  Also do block compression with
 * an adaptive reset, whereby the code table is cleared when the compression
 * ratio decreases, but after the table fills.  The variable-length output
 * codes are re-sized at this point, and a special CLEAR code is generated
 * for the decompressor.  Late addition:  construct the table according to
 * file size for noticeable speed improvement on small files.  Please direct
 * questions about this implementation to ames!jaw.
 */
void
compress(fdin, fdout)
	int		fdin;
	int		fdout;
{
	REG2	long		hp;
	REG3	int		rpos;
#if REGISTERS >= 5
	REG5	long		fc;
#endif
	REG6	int		outbits;
	REG7    int		rlop;
	REG8	int		rsize;
	REG9	int		stcode;
	REG10	code_int	free_ent;
	REG11	int		boff;
	REG12	int		n_bits;
	REG13	int		ratio;
	REG14	long		checkpoint;
	REG15	code_int	extcode;
	union {
		long		code;
		struct {
			char_type	c;
			unsigned short	ent;
		} e;
	} fcode;

	ratio = 0;
	checkpoint = CHECK_GAP;
	extcode = MAXCODE(n_bits = INIT_BITS)+1;
	stcode = 1;
	free_ent = FIRST;

	memset(outbuf, 0, sizeof(outbuf));
	bytes_out = 0; bytes_in = 0;
	outbuf[0] = MAGIC_1;
	outbuf[1] = MAGIC_2;
	outbuf[2] = (char)(maxbits | block_mode);
	boff = outbits = (3<<3);
	fcode.code = 0;

	clear_htab();

	while ((rsize = read(fdin, inbuf, IBUFSIZ)) > 0) {
		if (bytes_in == 0) {
			fcode.e.ent = inbuf[0];
			rpos = 1;
		} else
			rpos = 0;

		rlop = 0;

		do {
			if (free_ent >= extcode && fcode.e.ent < FIRST) {
				if (n_bits < maxbits) {
					boff = outbits = (outbits-1)+((n_bits<<3)- ((outbits-boff-1+(n_bits<<3))%(n_bits<<3)));
					if (++n_bits < maxbits)
						extcode = MAXCODE(n_bits)+1;
					else
						extcode = MAXCODE(n_bits);
				} else {
					extcode = MAXCODE(16)+OBUFSIZ;
					stcode = 0;
				}
			}

			if (!stcode && bytes_in >= checkpoint && fcode.e.ent < FIRST) {
				REG1 long int rat;

				checkpoint = bytes_in + CHECK_GAP;

				if (bytes_in > 0x007fffff) {	/* shift will overflow */
					rat = (bytes_out+(outbits>>3)) >> 8;

					if (rat == 0)		/* Don't divide by zero */
						rat = 0x7fffffff;
					else
						rat = bytes_in / rat;
				} else
					rat = (bytes_in << 8) / (bytes_out+(outbits>>3));	/* 8 fractional bits */

				if (rat >= ratio)
					ratio = (int)rat;
				else {
					ratio = 0;
					clear_htab();
					output(outbuf,outbits,CLEAR,n_bits);
					boff = outbits = (outbits-1)+((n_bits<<3)- ((outbits-boff-1+(n_bits<<3))%(n_bits<<3)));
					extcode = MAXCODE(n_bits = INIT_BITS)+1;
					free_ent = FIRST;
					stcode = 1;
				}
			}

			if (outbits >= (OBUFSIZ<<3)) {
				if (write(fdout, outbuf, OBUFSIZ) != OBUFSIZ)
					write_error();

				outbits -= (OBUFSIZ<<3);
				boff = -(((OBUFSIZ<<3)-boff)%(n_bits<<3));
				bytes_out += OBUFSIZ;

				memcpy(outbuf, outbuf+OBUFSIZ, (outbits>>3)+1);
				memset(outbuf+(outbits>>3)+1, '\0', OBUFSIZ);
			}

			{
				REG1 int i;

				i = rsize-rlop;

				if ((code_int)i > extcode-free_ent)	i = (int)(extcode-free_ent);
				if (i > ((sizeof(outbuf) - 32)*8 - outbits)/n_bits)
					i = ((sizeof(outbuf) - 32)*8 - outbits)/n_bits;

				if (!stcode && (long)i > checkpoint-bytes_in)
					i = (int)(checkpoint-bytes_in);

				rlop += i;
				bytes_in += i;
			}

			goto next;

hfound:			fcode.e.ent = codetabof(hp);
next:  			if (rpos >= rlop)
   				goto endlop;
next2: 			fcode.e.c = inbuf[rpos++];
#ifndef FAST
			{
				REG1 	code_int	i;
#if REGISTERS >= 5
				fc = fcode.code;
#else
#  define fc fcode.code
#endif
				hp = (((long)(fcode.e.c)) << (BITS-8)) ^
					(long)(fcode.e.ent);

				if ((i = htabof(hp)) == fc)
					goto hfound;

				if (i != -1) {
					REG4 long disp;

					/* secondary hash (after G. Knott) */
					disp = (HSIZE - hp)-1;

					do {
						if ((hp -= disp) < 0)	hp += HSIZE;

						if ((i = htabof(hp)) == fc)
							goto hfound;
					} while (i != -1);
				}
			}
#else
			{
				REG1 long i;
				REG4 long p;
#if REGISTERS >= 5
				fc = fcode.code;
#else
#  define fc fcode.code
#endif
				hp = ((((long)(fcode.e.c)) << (HBITS-8)) ^ (long)(fcode.e.ent));

				if ((i = htabof(hp)) == fc)
					goto hfound;
				if (i == -1)
					goto out;

				p = primetab[fcode.e.c];
lookup:				hp = (hp+p)&HMASK;

				if ((i = htabof(hp)) == fc)
					goto hfound;
				if (i == -1)
					goto out;

				hp = (hp+p)&HMASK;

				if ((i = htabof(hp)) == fc)
					goto hfound;
				if (i == -1)
					goto out;

				hp = (hp+p)&HMASK;

				if ((i = htabof(hp)) == fc)
					goto hfound;
				if (i == -1)
					goto out;
				goto lookup;
			}
out:			;
#endif
			output(outbuf,outbits,fcode.e.ent,n_bits);

			{
#if REGISTERS < 5
#	undef	fc
				REG1 long fc;
				fc = fcode.code;
#endif
				fcode.e.ent = fcode.e.c;


				if (stcode) {
					codetabof(hp) = (unsigned short)free_ent++;
					htabof(hp) = fc;
				}
			}

			goto next;

endlop:			if (fcode.e.ent >= FIRST && rpos < rsize)
				goto next2;

			if (rpos > rlop) {
				bytes_in += rpos-rlop;
				rlop = rpos;
			}
		} while (rlop < rsize);
	}

	if (rsize < 0)
		read_error();

	if (bytes_in > 0)
		output(outbuf,outbits,fcode.e.ent,n_bits);

	if (write(fdout, outbuf, (outbits+7)>>3) != (outbits+7)>>3)
		write_error();

	bytes_out += (outbits+7)>>3;

	return;
}


/*
 * Decompress stdin to stdout.  This routine adapts to the codes in the
 * file building the "string" table on-the-fly; requiring no table to
 * be stored in the compressed file.  The tables used herein are shared
 * with those of the compress() routine.  See the definitions above.
 */

void
decompress(fdin, fdout)
	int		fdin;
	int		fdout;
{
	REG2 	char_type 	*stackp;
	REG3	code_int	 code;
    	REG4	int		 finchar;
	REG5	code_int	 oldcode;
	REG6	code_int	 incode;
	REG7	int		 inbits;
	REG8	int		 posbits;
	REG9	int		 outpos;
	REG10	int		 insize;
	REG11	int		 bitmask;
	REG12	code_int	 free_ent;
	REG13	code_int	 maxcode;
	REG14	code_int	 maxmaxcode;
	REG15	int		 n_bits;
	REG16	int		 rsize;

	bytes_in = 0;
	bytes_out = 0;
	insize = 0;

	while (insize < 3 && (rsize = read(fdin, inbuf+insize, IBUFSIZ)) > 0) {
		insize += rsize;
	}

	if (insize < 3 || inbuf[0] != MAGIC_1 || inbuf[1] != MAGIC_2) {
		if (rsize < 0)
			read_error();

		if (insize > 0) {
			fprintf(stderr, "%s: not in compressed format\n",
				(ifname[0] != '\0'? ifname : "stdin"));
			exit_code = 1;
		}

		return;
	}

	maxbits = inbuf[2] & BIT_MASK;
	block_mode = inbuf[2] & BLOCK_MODE;
	maxmaxcode = MAXCODE(maxbits);

	if (maxbits > BITS) {
		fprintf(stderr,
		    "%s: compressed with %d bits, can only handle %d bits\n",
		    (*ifname != '\0' ? ifname : "stdin"), maxbits, BITS);
		exit_code = 4;
		return;
	}

	bytes_in = insize;
	maxcode = MAXCODE(n_bits = INIT_BITS)-1;
	bitmask = (1<<n_bits)-1;
	oldcode = -1;
	finchar = 0;
	outpos = 0;
	posbits = 3<<3;

	free_ent = ((block_mode) ? FIRST : 256);

	clear_tab_prefixof();	/* As above, initialize the first */
				/* 256 entries in the table. */

	for (code = 255 ; code >= 0; --code)
		tab_suffixof(code) = (char_type)code;

	do {
resetbuf:	;
		{
			REG1 int i;
			int e;
			int o;

			e = insize - (o = (posbits>>3));

			for (i = 0 ; i < e ; ++i)
				inbuf[i] = inbuf[i + o];

			insize = e;
			posbits = 0;
		}

		if (insize < sizeof(inbuf)-IBUFSIZ) {
			if ((rsize = read(fdin, inbuf+insize, IBUFSIZ)) < 0)
				read_error();

			insize += rsize;
		}

		inbits = ((rsize > 0) ? (insize - insize%n_bits)<<3 :
			(insize<<3)-(n_bits-1));

		while (inbits > posbits) {
			if (free_ent > maxcode) {
				posbits = ((posbits-1) + ((n_bits<<3) -
					 (posbits-1+(n_bits<<3))%(n_bits<<3)));

				++n_bits;
				if (n_bits == maxbits)
					maxcode = maxmaxcode;
				else
					maxcode = MAXCODE(n_bits)-1;

				bitmask = (1<<n_bits)-1;
				goto resetbuf;
			}

			input(inbuf,posbits,code,n_bits,bitmask);

			if (oldcode == -1) {
				outbuf[outpos++] = (char_type)(finchar = (int)(oldcode = code));
				continue;
			}

			if (code == CLEAR && block_mode) {
				clear_tab_prefixof();
				free_ent = FIRST - 1;
				posbits = ((posbits-1) + ((n_bits<<3) -
					(posbits-1+(n_bits<<3))%(n_bits<<3)));
				maxcode = MAXCODE(n_bits = INIT_BITS)-1;
				bitmask = (1<<n_bits)-1;
				goto resetbuf;
			}

			incode = code;
			stackp = de_stack;

			if (code >= free_ent) {	/* Special case for KwKwK string. */
				if (code > free_ent) {
					REG1 char_type 		*p;

					posbits -= n_bits;
					p = &inbuf[posbits>>3];

					fprintf(stderr, "insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)\n", insize, posbits,
							p[-1],p[0],p[1],p[2],p[3], (posbits&07));
		    			fprintf(stderr, "uncompress: corrupt input\n");
					abort_compress();
				}

        	  		*--stackp = (char_type)finchar;
	    			code = oldcode;
			}

			/* Generate output characters in reverse order */
			while ((cmp_code_int)code >= (cmp_code_int)256) {
		    		*--stackp = tab_suffixof(code);
		    		code = tab_prefixof(code);
			}

			*--stackp = (char_type)(finchar = tab_suffixof(code));

			/* And put them out in forward order */

			{
				REG1 int	i;

				if (outpos+(i = (de_stack-stackp)) >= OBUFSIZ) {
					do {
						if (i > OBUFSIZ-outpos)
							i = OBUFSIZ-outpos;

						if (i > 0) {
							memcpy(outbuf+outpos, stackp, i);
							outpos += i;
						}

						if (outpos >= OBUFSIZ) {
							if (write(fdout, outbuf, outpos) != outpos)
								write_error();

							outpos = 0;
						}
						stackp+= i;
					}
					while ((i = (de_stack-stackp)) > 0);
				} else {
					memcpy(outbuf+outpos, stackp, i);
					outpos += i;
				}
			}

			/* Generate the new entry. */
			if ((code = free_ent) < maxmaxcode) {
		    		tab_prefixof(code) = (unsigned short)oldcode;
		    		tab_suffixof(code) = (char_type)finchar;
    				free_ent = code+1;
			}

			oldcode = incode;	/* Remember previous code.	*/
		}

		bytes_in += rsize;
	} while (rsize > 0);

	if (outpos > 0 && write(fdout, outbuf, outpos) != outpos)
		write_error();
}

void
read_error()
{
	fprintf(stderr, "\nread error on");
	perror((ifname[0] != '\0') ? ifname : "stdin");
	abort_compress();
}

void
write_error()
{
	fprintf(stderr, "\nwrite error on");
	perror((ofname[0] != '\0') ? ofname : "stdout");
	abort_compress();
}

void
abort_compress()
{
	if (remove_ofname)
	    	unlink(ofname);

	exit(1);
}

void
prratio(stream, num, den)
	FILE		*stream;
	long int	 num;
	long int	 den;
{
	REG1 int q;			/* Doesn't need to be long */

	if (den > 0) {
		if (num > 214748L)
			q = (int)(num/(den/10000L));	/* 2147483647/10000 */
		else
			q = (int)(10000L*num/den);	/* Long calculations, though */
	} else
		q = 10000;

	if (q < 0) {
		putc('-', stream);
		q = -q;
	}

	fprintf(stream, "%d.%02d%%", q / 100, q % 100);
}

void
about()
{
	fprintf(stderr, "Compress version: %s, compiled: %s\n", version_id, COMPILE_DATE);
	fprintf(stderr, "Compile options:\n        ");
#if BYTEORDER == 4321 && NOALLIGN == 1
	fprintf(stderr, "USE_BYTEORDER, ");
#endif
#ifdef FAST
	fprintf(stderr, "FAST, ");
#endif
#ifdef vax
	fprintf(stderr, "vax, ");
#endif
#ifdef DIRENT
	fprintf(stderr,"DIRENT, ");
#endif
#ifdef SYSDIR
	fprintf(stderr,"SYSDIR, ");
#endif
#ifdef NO_UCHAR
	fprintf(stderr, "NO_UCHAR, ");
#endif
#ifdef SIGNED_COMPARE_SLOW
	fprintf(stderr, "SIGNED_COMPARE_SLOW, ");
#endif
#ifdef MAXSEG_64K
	fprintf(stderr, "MAXSEG_64K, ");
#endif
#ifdef DOS
	fprintf(stderr, "DOS, ");
#endif
#ifdef DEBUG
	fprintf(stderr, "DEBUG, ");
#endif
#ifdef LSTAT
	fprintf(stderr, "LSTAT, ");
#endif
	fprintf(stderr, "\n        REGISTERS=%d IBUFSIZ=%d, OBUFSIZ=%d, BITS=%d\n",
			REGISTERS, IBUFSIZ, OBUFSIZ, BITS);

	fprintf(stderr, "\n\
Author version 4.2 (Speed improvement & source cleanup):\n\
     Peter Jannesen  (peter@ncs.nl)\n\
\n\
Author version 4.1 (Added recursive directory compress):\n\
     Dave Mack  (csu@alembic.acs.com)\n\
\n\
Authors version 4.0 (World release in 1985):\n\
     Spencer W. Thomas, Jim McKie, Steve Davies,\n\
     Ken Turkowski, James A. Woods, Joe Orost\n");

	exit(0);
}
